21934009 has 4 divisors (see below), whose sum is σ = 21944704. Its totient is φ = 21923316.

The previous prime is 21933971. The next prime is 21934013. The reversal of 21934009 is 90043912.

It is a happy number.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4, and also a brilliant number, because the two primes have the same length.

It is a cyclic number.

It is not a de Polignac number, because 21934009 - 2²³ = 13545401 is a prime.

It is a super-2 number, since 2×21934009² = 962201501624162, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21934039) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1197 + ... + 6730.

It is an arithmetic number, because the mean of its divisors is an integer number (5486176).

Almost surely, 2^21934009 is an apocalyptic number.

It is an amenable number.

21934009 is a deficient number, since it is larger than the sum of its proper divisors (10695).

21934009 is an equidigital number, since it uses as much as digits as its factorization.

21934009 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 10694.

The product of its (nonzero) digits is 1944, while the sum is 28.

The square root of 21934009 is about 4683.3758123815. The cubic root of 21934009 is about 279.9234867468.

The spelling of 21934009 in words is "twenty-one million, nine hundred thirty-four thousand, nine".